Automatic railless ground conveyor installation

ABSTRACT

An automatic railless ground conveyor installation comprising a passive guide track determining the route network and individual driverless or unmanned traveling conveyor cars, each of which possesses a steering mechanism scanning in a contactless manner the guide track. The steering mechanism comprises a central scanning element which during straight ahead travel of the conveyor car is located over the guide track and after turning of the conveyor car onto the guide track serves to reset the steering deflection of the conveyor car and at least two scanning elements arranged to each side of the central scanning element at a progressively increasing distance therefrom. The outermost scanning elements when activated by the guide track serve to trigger a greater steering deflection than the inner situated scanning elements.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of our commonly assigned,copending United States application Ser. No. 481,897, filed June 21,1974, now U.S. Pat. No. 3,948,342.

BACKGROUND OF THE INVENTION

The present invention relates to a new and improved construction ofautomatic railless ground conveyor installation of the type comprising apassive guide track which defines the route or stretch network andindividual driverless or unmanned traveling conveyor cars or vehicles,each of which is equipped with a steering mechanism which scans in acontactless manner the guide track as well as a work control mechanismwhich contains a code reader in order to scan in a contactless mannerindividual code markings arranged at branches and identifying the sameand directly influencing the steering mechanism in the sense of reachinga target or destination determined by a target code set at the workcontrol mechanism.

Automatic trackless or railless ground conveyor installations of thepreviously mentioned type have become known to the art from the GermanPat. No. 1,481,482, corresponding to U.S. Pat. No. 3,474,877. Theconveyor cars of such ground conveyor installation are associated withthe difficulty of exactly guiding such along the guide track since atthe branching-off locations of the guide track, the so-called branchesor junctions, the conveyor cars each carry out the same steeringdeflection irrespective of the deviation of the conveyor car from theguide track. This results in a certain compromise with regard to themagnitude of the steering deflection, with the result that thecorrection deflection is too great in those instances where there is asmall branching-off from the guide track and too small in thoseinstances where there is a more pronounced branching-off. As a resultthe conveyor car begins to oscillate. Moreover, the work controlmechanism of such conveyor car is complicated since in the case of abranch-off location at a junction or branch which must be detected as afunction of the target code the steering mechanism must deliver acommand for achieving a positive steering deflection.

SUMMARY OF THE INVENTION

Hence, it is a primary object of the present invention to provide animproved construction of automatic railless ground conveyor installationof the previously mentioned type which is not associated with theaforementioned drawbacks and limitations of the prior art proposals.

A further object of the present invention aims at the provision of asteering mechanism for an automatic railless ground conveyorinstallation of the previously mentioned type, which notwithstanding itssimple construction insures for a good guiding of the conveyor car alongthe track and permits simplification of the construction of the workcontrol mechanism and the steering mechanism.

Now in order to implement these and still further objects of theinvention, which will become more readily apparent as the descriptionproceeds, the automatic railless ground conveyor installation of theinvention is manifested by the features that the steering mechanismcomprises a central scanning element which during straight ahead travelof the conveyor car is located over the guide track and after turning ofthe conveyor car onto the guide track serves to reset the steeringdeflection of the conveyor car. At least two scanning elements arearranged to both sides of the central scanning element at aprogressively increasing distance therefrom and transversely withrespect to the direction of travel. The outermost scanning elements whenactivated by the guide track serve to trigger a greater steeringdeflection than the inner situated scanning elements.

By virtue of the fact that the steering mechanism for scanning the guidetrack possesses, apart from a central scanning element, at both sidesfirst scanning elements which bring about a smaller correctiondeflection, the conveyor car can be precisely corrected in the case ofsmall deviations from the guide track. With greater deviations andparticularly also in the case of branch-off locations the scanningelements arranged at a greater distance from the central scanningelement become active and bring about a greater steering deflectionwhich initially brings the conveyor car more rapidly into coincidence oralignment with the guide track. The remaining correction again can beperformed by the first scanning elements situated closer to the centralscanning element.

A particularly simple construction of the railless ground conveyorinstallation is realized when the steering mechanism possesses a camswitching mechanism operatively coupled with a steering drive andmovable in proportion to the steering movement. Each scanning elementhas operatively associated therewith a cam disk cooperating withswitching elements. Switching cam means of the central scanning elementduring its activation by the guide track and with turned steering closesa resetting current circuit for the steering motor and with the steeringturned back interrupts the resetting current circuit. Switching cammeans of the remaining scanning elements are arranged such that in orderto limit the steering deflection they interrupt a drive current circuitof the steering motor. Instead of the cam switching mechanism forcontrolling the steering mechanism it would of course be possible to useother equipment structures such as an standard optical are anglemeasuring device.

A particularly advantageous construction of the steering mechanism isconstituted by a so-called crank loop drive, wherein a crank pin thereofis located at the center of the loop during straight ahead travel of theconveyor car. Thus, with the same pivot angle of the crank pin theincipient steering deflections are smaller than those arising at a laterperiod of time. In this way there can be realized a particularlysensitive steering of the conveyor car with small steering deflections.

An extremely preferred constructional manifestation of the invention isrealized if the steering mechanism is directly coupled with the targetcode mechanism, so that in those instances where the conveyor car shouldnot turn-off at the branch the outermost scanning element associatedwith the branch-off location is disconnected or rendered ineffectual. Inother words, in the case of branching-off of the conveyor car at abranch which is determined by the target code mechanism thecorresponding outermost scanning element detects the branch-off locationand causes the steering mechanism to appropriately turn or deflect.Consequently, it is no longer necessary to impart to the steeringmechanism as a function of the target code a positive steering pulse inthe event that the conveyor car is to branch-off at a branch. Thisconstruction also renders to possible for the conveyor cars to travelover intersections, so that when it is not desired for the conveyor carto branch-off in the one or the other direction both outermost scanningelements can be disconnected. In the case where the conveyor car shouldbranch-off in one direction it is only necessary to disconnect theoppositely situated outermost scanning element. In the case of abranch-off command the associated outermost scanning element takesprecedence relative to the remaining scanning elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those setforth above, will become apparent when consideration is given to thefollowing detailed description thereof. Such description makes referenceto the annexed drawings wherein:

FIG. 1 schematically illustrates in plan view a section of the stretchor route network of the ground conveyor installation of thisdevelopment;

FIG. 2 illustrates in plan view of one of the conveyor cars with exposeddrive- and control components;

FIG. 3 illustrates in side view part of the steering mechanism;

FIG. 4 is a plan view of the steering mechanism depicted in FIG. 3;

FIG. 5 is a block circuit diagram of the steering mechanism and thefunction or work control mechanism.

FIG. 6 illustrates a route branch or junction with a continuous branchcode track and a marker;

FIG. 7 illustrates a branch or junction likewise with a continuous oruninterrupted branch code track and a forwardly located supplementarycode track which extends parallel to the guide track;

FIG. 8 illustrates a branch with a branch code track formed by aninterruption of the guide track;

FIG. 9 illustrates a branch according to the showing of FIG 8, howeverwith a continuous or uninterrupted supplementary code track; and

FIG. 10 illustrates details of a length measuring device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Describing now the drawings, in FIG. 1 there is illustrated a section ofa route or stretch network at which a guide track A branches off at thejunctions or branches B₁ and B₂ into guide tracks A₁ and A₂ constitutingsidings or branched-off locations. The guide tracks are passive, i.e.they do not deliver any pulses. They can be, for instance, coloredstrips, bands or tapes formed of ferromagnetic material, metallic bandsor tapes or so forth. In front of the route branches B₁ and B₂ there arearranged in each case the branch code tracks C₁ and C₂ constituting thebranch codes, and which in the embodiment under discussion arethemselves formed by the guide track. The length of the branch codetracks is determined by a supplementary code track D₁ located in frontof the start of each of the branch code tracks C₁ and C₂, suchsupplementary code tracks D₁ not only marking or designating the startof the branch code tracks C₁ and C₂, but furthermore containing asupplementary code designated as "branch". In front of suchsupplementary code track D₁, and parallel to the guide track A, therecan be arranged an auxiliary track E which alerts the code reading orreader mechanism to the fact that a supplementary code track must bescanned. This auxiliary track can also additionally trigger auxiliaryfunctions in the conveying or conveyor cars.

At the siding or branch of the stretch formed by the guide track A₁there is likewise arranged a supplementary code track D₂ which activatesa story code mechanism which will be described more fully hereinafter inorder to cause a subsequently connected transmitter to transmit a storycode which should be received by a receiver 10 arranged at the stretch.The receiver 10 serves to recall and, if necessary, code a lift orelevator.

Traveling over the guide track is a schematically illustrated conveyorcar 12 having a forwardly arranged and rearwardly arranged rapid stopfeeler 14 for stopping the conveyor car when it strikes a hinderance orobstruction. The rapid stop feelers or high-speed stop feelers 14 are,for instance, hydraulically or pneumatically acting contact switcheswhich are preferably constructed as hose loops. Furthermore, theconveyor car is equipped with forward and rearward situated scanning orfeeler heads 22 serving to guide the conveyor car along the guide trackA and for diverting such at the branches B₁ and B₂.

Additionally, there is also illustrated a programming transmitter 18which is arranged at the stretch or network, the construction and modeof operation of which will be discussed more fully hereinafter.

The conveyor car 12 which has been shown in FIG. 2 again has beenillustrated to possess the high-speed operating stop feelers 14 at thefront and rear end of such car. It also contains a steering or guidemechanism 20 embodying a feeler or scanner head 22, the steering driveor transmission 24, a steering motor 26 as well as a cam switchingmechanism 28. Such steering mechanism is arranged at the front end ofthe conveyor car. Drive wheels 30 are actuated by the drive motors 32.The conveyor car also contains a work control mechanism 34.

FIGS. 3 and 4 illustrate details of the steering mechanism 20 portrayedin FIG. 2, of which there is arranged a unit at the front end of theconveyor car. The rapid stop feeler 14 and the scanning head 22 arearranged both at the front as well as also at the rear end, whereinhowever in each instance only the components located at the front in thedirection of travel are activated. The conveyor or conveying carstherefore can travel both forwards and backwards.

The rapid stop mechanism is constructed such that it again positivelyplaces into operation the conveying cars, if desired with a certaintime-delay, but in any event as soon as the obstruction or hinderance isremoved. The rapid stop mechanism therefore not only functions as anemergency device but also as the active control element of the groundconveyor installation. The conveyor cars can travel without damage in anirregular sequence and can hit one another. The blocking stretches orpaths required with the prior art ground conveyor installations are nolonger necessary, since the rapid stopping mechanisms assume theirfunction.

The steering mechanism 20 possesses the scanning or feeler head 22 whichcontains five scanning or feeler elements 36. A central scanning orfeeler element 36₁, which is located over the guide track A whentraveling straight ahead, serves the purpose, after turning ordeflecting the conveyor car onto the guide track, of bringing aboutresetting of the turning or steering deflection. Transversely withrespect to the conveying direction and to both sides of the centralscanning element 36₁ there are located at a slight spacing therefrom thefirst scanning elements 36₂. Activation of the first scanning elements36₂ brings about only a small steering deflection or turning effect andserves to correct the conveyor car during slight deviations from theguide track. At progressively larger spacing there are arranged towardsthe outside at both sides of the first scanning elements 36₂ the secondscanning elements 36₃ which, during greater deviations of the conveyorcar, especially when travelling in curves and at branches, come intoplay and bring about a greater steering deflection. The scanningelements 36 are operatively connected with the cam switching mechanism28, wherein each scanning element has associated therewith a cam disk38, the switching cams 40 of which cooperate with switching elements 2.The cam switching mechanism 28 is coupled through the intermediary of atoothed belt 44 with a steering drive 46 which is driven from a steeringmotor 48 likewise through the agency of a toothed belt 50. The steeringdrive or transmission contains a crank guide drive, the crank pin 52 ofwhich, during the time that the steering roller 54 travels straightahead, is located at the center of a loop 56. In order to permit abetter null point correction in this instance the loop 56 is sub-dividedinto two halves, wherein in the one half of such loop the crank pin 52engages during the movement towards the left and in the other halfthereof there engages a crank pin during the movement towards the right.The arm 58 carrying the loop is connected with the steering roller 54.

During the straightahead movement of the conveyor car the switching cams40₂ and 40₃ of the outer scanning elements 36₂ and 36₃ do not cooperatewith the switching elements 42₂ and 42₃, so that their contacts bearagainst the cam disks. Now if one of the outer scanning elements 36₂ or36₃ is activated by the guide track A, then via the switching elements42₂ or 42₃ and the corresponding cam disk 38 there is closed a currentcircuit which energizes the steering motor 48, so that a deflection orturning of the steering roller 54 occurs. The deflection continues forsuch time until the switching cams 40 of the corresponding scanningelement 36 travel onto the associated switching element 42 and interruptthe current circuit, so that no further deflection or turning occurs.The conveyor car then travels back onto the guide track until thecentral scanning element 36₁ is energized by the guide track. Since theswitching cam 40₁, during a turning deflection, is not in engagementwith the switch 42₁ it closes via the associated cam disk 38 a resettingcurrent circuit which causes the steering motor 48 to rotate in theopposite direction, i.e. again sets straight the steering roller 54. Theresetting of the roller occurs for such length of time until theswitching cam 40₁ bears against the switching element 42₁ and interruptsthe resetting current circuit.

In FIG. 5 there is illustrated the block circuit diagram of a conveyorcar for the work mechanism 34 and the steering mechanism 20. The mode ofoperation of the steering mechanism 20 has been described in detailheretofore, so that at this point there is only additionally mentionedthat the steering control 60 contains the cam switching mechanism 28.The work control mechanism contains two or three main groups, the targetor destination code mechanism which is sub-divided into the branch codemechanism with the comparator 62 and the storage 64 and the story codemechanism with the storage 66 and the transmitter 68, and thesupplementary code mechanism containing the storage 70, the comparator72 and the command receiver 74 which is activated by a commandtransmitter 76 at the stretch or network. Common to all of themechanisms is a proramming device or mechanism 78 which can beprogrammed either by a manual programming device 80 or by a programmingreceiver 82 which receives its signals from a programming transmitter18. As the reading mechanism or reader of the work control mechanismthere is used the central scanning element 36₁ of the steeringmechanism, which is connected with a length measuring unit or device 84.Connected thereafter are the comparators 62 and 72 of the branch codemechanism and the supplementary code mechanism, respectively. The lengthmeasuring unit 84 is, for instance, constituted by a counting wheelwhich parallely travels with a drive wheel of the conveyor car and foreach unit length delivers a certain number of pulses, as will beexplained more fully hereinafter in conjunction with FIG. 10. The workcontrol mechanism furthermore contains an auxiliary reading element 86which responds to the auxiliary track E and is connected with the lengthmeasuring unit.

Further details of the construction and the mode of operation of thework control mechanism are as follows: It is possible to program theprogramming mechanism either by means of the manual programmingmechanism or device 80 or preferably by means of the programmingreceiver 82 which is supplied by means of the programming transmitter18, and which are preferably ultrasonic receivers and transmitters. Theycan operate for instance with four carrier frequencies and transmitbinary coded signals. The programming device is for instance coupled bymeans of four respective lines or conductors with the storages 64, 70and 66 of the branch code-, supplementary code- and storycode-mechanisms. These storages are preferably constructed as flip-flopstorages. With the four infeed lines it is possible to transmit up tosixteen commands. At a station, via the programming transmitter 18,ultrasonic signals are introduced in binary coded form to theprogramming receiver 82 and specifically, for instance, a target ordestination code having three numbers between 1 and 10. Aftertermination of such transmission the target code is transmitted to allthree flip-flop storages. A fourth switching element subsequentlyrenders the flip-flop storages 64 and 66 non-responsive to any furtherreception, whereas the flip-flop storage 70 of the supplementary codemechanism is capable of receiving further supplementary codes during thetravel of the car and to transform such into appropriate commands.

If a thus programmed conveyor car travels along the stretch of FIG. 1,then the steering mechanism 20 scans with the aid of its scanning orfeeler element 36₁ the guide track. If the auxiliary reading element 86reaches the auxiliary track E, then, it delivers to the length measuringunit 84 a command that it must count upon arrival at the supplementarycode track D₁. If the central scanning element 36₁ reaches thesupplementary code track D₁, which is formed by omitting the guide trackalong a certain path, then the central scanning element 36₁ transmits asignal to the length measuring unit at which there is measured thelength of the supplementary code track D₁. The output of the lengthmeasuring unit is coupled with the comparator 72 of the supplementarycode mechanism 70. The measured length of the supplementary code trackD₁ must now coincide with the code stored in the supplementary codemechanism for the command branch or "switch". Then the comparatorgenerates an output signal which is further transmitted to the lengthmeasuring unit 84 and switches such to the comparator 62. During furthertravel of the conveyor car there now occurs a length measurement of thebranch code C₁. At the moment when the comparator 62 is connected withthe length measuring unit 84, it delivers a signal to the length controlwhich brings about that the outer scanning elements 36₃ areswitched-off, i.e. they cannot recognize any branching or siding. Thecomparator 62 now continuously compares the length of the branch codetrack C₁ with the branch code which has been introduced. into thestorage 64. If the branch code is shorter than the branch code track C₁then the comparator again delivers an output signal which at thesteering control 60 brings about an activation of the outer scanningelements 36₃. During further travel of the conveyor car these outerscanning elements 36₃ can recognize or detect the siding or branch A₁and the conveyor car turns off. On the other hand, if the branch codecontained in the storage 64 is longer than the branch code track C₁,then during the scanning of the branch code track C₁ there does notoccur any activation of the outer scanning elements 36₃, rather first atthe end of the branch code track C₁. In this position, however, thescanning head of the conveyor car is already past the siding or branchA₁, so that the conveyor car continues to travel straight ahead and doesnot turn off. In this way there can be achieved the result that, forinstance, with ten different length branch code tracks C there can bedetected ten different junctions or branches. It should be apparent thatthere are not required any further active control elements along thestretch or network.

If the conveyor car travels along the branch or siding with the guidetrack A₁, then it arrives at the supplementary code track D₂ whichsignifies "Call Lift". The signal delivered by the central scanningelement 36₁ at the length measuring unit 84 again arrives at thecomparator 72 which compares the measured length with the supplementarycodes of the storage 70. Consequently it determines that thesupplementary code track D₂ intends to call the lift and transmits viaits output connected with the transmitter 68 a signal for activating thetransmitter. Such transmits the story code contained in the storage 66to the receiver 10 arranged at the network, whereupon such calls andprograms a lift or elevator. The lift basket can only possess a singleguide track for the ascending as well as also for the descendingdirection of travel.

The supplementary code mechanism not only contains a comparator 72connected with the length measuring unit 84, rather also a commandreceiver 74 which responds to a command transmitter 76 along theconveying path. By means of this command transmitter, which likewise canfunction with ultrasonic energy, it is possible to transmit differentcommands of the supplementary code mechanism. The comparator 72 and thecommand receiver 74 further possess different common outputs 88 whichcan be connected with different devices of the conveyor car in order totrigger appropriate functions. Thus, the supplementary code mechanismcan serve the purpose of generating further travel signals, such as,start of the travel, turning, half-speed travel, opening or closing ofthe scanning elements, full speed travel, engaging or disengaging thecoupling and the like.

In FIGS. 6 to 9 there are illustrated different variant constructions ofthe branch code track and the supplementary code track.

In FIG. 6 the branch code track C₃ again is constituted by a continuousi.e. non-interrupted line of the guide track A, the start of the branchcode track C₃ being determined by a marker F. With this embodiment thereis not present any supplementary code track in front of the start of thebranch code track C₃.

FIG. 7 likewise illustrates a continuous branch code track C₄ which isformed by the guide line A, and the start of which is determined by asupplementary code track D₃. This supplementary code track is locatedparallel to the guide track A.

FIG. 8 illustrates a branch code track C₅ which is formed by aninterruption of the guide line or track A along the length of the branchcode track.

FIG. 9 corresponds to FIG. 8, however in this case there is located atthe start of the branch code track C₅ a supplementary code track D₄which is formed by a continuous line of the guide track A and the startof which is determined by a marker F.

FIG. 10 illustrates a possible arrangement of the length measuringdevice or unit wherein a disk 100 is located for example at the drivewheel 30 of the car 12. The disk 100 is provided along a circle withmarkings 101 having uniform spacing from one another. This spacing cancorrespond for instance to a length unit of the traveled path. Thesemarkings 101, which for instance can consist of metal strips, can bescanned by a scanning device 102 fixedly arranged at a frame of the carand which scanning device 102 then obviously would be part of the lengthmeasuring unit 84 of the block circuit diagram of FIG. 5. Duringrotation of the disk 100 the markings 101 move past the scanning device102 as a function of the path through which the car has traveled. Thescanning device 102 then can deliver a number of pulses corresponding tothe rotation of the disk 100 and thus the length of travel of the car.

While there is shown and described present preferred embodiments of theinvention, it is to be distinctly understood that the invention is notlimited thereto but may be otherwise variously embodied and practicedwithin the scope of the following claims. Accordingly,

What is claimed is:
 1. An automatic railless ground conveyorinstallation comprising a guide track for defining a route networkhaving branches, a number of individual driverless traveling conveyorcars, each of said conveyor cars possessing steering mechanism for thecontactless scanning of the guide track and a work control mechanism,said work control mechanism including code reading means for thecontactless scanning of individual code markings identifying thebranches and directly influencing the steering mechanism in the sense ofreaching a destination determined by a target code set at the workcontrol mechanism, the steering mechanism comprising a central scanningelement which during straight ahead travel of the conveyor car islocated over the guide track and after turning of the conveyor car ontothe guide track serves to reset the steering deflection of the conveyorcar, and at least two scanning elements arranged to each side of thecentral scanning element at progressively increasing distance therefromand transversely arranged with respect to the direction of conveyor cartravel, the outermost scanning elements when activated by the guidetrack serve to trigger a greater steering deflection than the innersituated scanning elements.
 2. The ground conveyor installation asdefined in claim 1, wherein the steering mechanism comprises a steeringdrive including a steering motor, a cam switching mechanism operativelycoupled with the steering drive and movable proportional to the steeringmovement, each scanning element having operatively associated therewitha cam disk cooperating with switching elements, the scanning elementshaving switching cam means, the switching cam means of the centralscanning element during its activation by the guide track and withturned steering closing a resetting current circuit for the steeringmotor and interrupting the resetting current circuit when the steeringis turned back, and the switching cam means of the remaining scanningelements are arranged such that for limiting the steering deflectionthey interrupt a drive current circuit of the steering motor which isclosed upon activation of one of the outermost scanning elements.
 3. Theground conveyor installation as defined in claim 1, wherein the steeringmechanism comprises a crank guide drive means including crank pin mens,loop means cooperating with said crank pin means, said crank pin meansbeing located at the center of said loop means when the conveyor cartravels substantially straight ahead.
 4. The ground conveyorinstallation as defined in claim 1, wherein the steering mechanism iscoupled with the target code mechanism such that for branching off ofthe conveyor car at a branch the outermost scanning element associatedwith the branch is activated.
 5. The ground conveyor installation asdefined in claim 1, wherein the steering mechanism comprises a steeringdrive including a steering motor, a mechanism operatively coupled withthe steering drive and movable proportional to the steering movementeach scanning element having operatively associated therewith switchingmeans, the switching means of the central scanning element during itsactivation by the guide track and with turned steering closing aresetting current circuit for the steering motor and interrupting theresetting current circuit when the steering is turned back, and theswitching means of the remaining scanning elements are arranged suchthat for limiting the steering deflection they interrupt a drive currentcircuit of the steering motor which is closed upon activation of one ofthe outermost scanning elements.